This invention relates to printwheels used in a printing apparatus and more particularly to printwheels having multiple sets of character or symbol type fonts.
In the prior art, daisywheel printers are quite well known, and, in fact, have enjoyed a large commercial acceptance as a high quality impact printer. While daisywheel printers have most often been used in applications requiring a large character set (typical daisywheel printwheels have ninety-six different character and symbol fonts or type face disposed at the ends of the spokes of the wheel), some specialized applications have made use of significantly fewer different fonts. These applications include numeral printers (printers which apply the magnetic ink numerals and symbols at the bottom of bank checks are exemplary numeral printers), printers used for graphics and plotting and printers used for facsimilie reproduction. In each of these applications, the character set is significantly shorter than the normal 96 character alphanumeric printwheel. Also, it should be evident that as the character set decreases in size, the useage rate of the individual characters or symbols increases. Because these printers are impact printers, the character fonts, with time, will either wear out or distruct.
To prolong the effective life of printwheels used in such applications, prior art printwheels have been equipped with multiple sets of these shorter character sets on a single wheel. Note FIG. 1, where such a printwheel is identified by numeral 1 and where each of the multiple sets is identified by the letter A. The printwheel 1 has a central hub 11 in which is disposed a single index hole 12. The printer is typically controlled by a programmable device, which, in this instance, is especially programmed to select different character sets as each set wears out or destructs. The disadvantage of such specialized programming is, of course, the necessity and cost of having it written.
It was, therefore, one object of this invention to improve such printers to alleviate the need to provide such specialized programming but still provide a printwheel with multiple sets of character fonts.